On a map, a closed shape defined by a connected sequence of x,y coordinate pairs, where the first and last coordinate pair are the same and all other pairs are unique.

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2
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3answers
1k views

Accessing coordinates of polygon

I have designed a polygon in a web page and the coordinates are stored in the database of the type polygon. However when I check the database, I find GEOMETRY - 120B under polygon field. What does ...
2
votes
3answers
3k views

How to aggregate points to polygons using ArcGIS Desktop?

I am trying to aggregate my data points to the polygons so that I could find out how many points I actually have in each polygon, and then export the data contained within each polygon to further look ...
0
votes
1answer
262 views

How to remove polygon under other one?

Hi, lets say that green polygon is under red and part of blue with yellow stripes is also under red polygon. how can i make one polygon from every polygons that intersects my main ( red ) polygon ...
9
votes
1answer
2k views

Postgis - Converting 'geometry_dump' data type to a 'geometry' type

I am working with a dataset of property boundaries that has had ST_Union() run on it, thus all the polygons appear as a multi polygon in one row of a table. I would like to separate these out so I get ...
3
votes
2answers
810 views

Merging polygons that intersect by more than a specified amount

I am working with a dataset that contains a subset of property boundaries in a local government area, thus my dataset is made up of several thousand properties but not all are touching. Since it is a ...
1
vote
1answer
647 views

How to color markers based on polygon area?

I have a map with around 317 markers and each marker is the center point of a polygon. The polygonal area varies throughout, so I want to represent the markers in such a way that the polygon with the ...
8
votes
5answers
7k views

How do I convert a Polygon into a single or all Points?

I want to convert polygons into points. I know how it's done in ArcGis and I think this may sound trivial but it's a serious issue :/. I'll appreciate any hints :)
3
votes
1answer
1k views

Changing the scale (generalisation) in ArcGIS 10

I have 2 polygon layers, accordingly 1:10 000 and 1:500 000. I want to generalize the first layer from 1:10 000 to 1:500 000. I tried using Simplify polygon tool, and since these scales relate to ...
5
votes
2answers
3k views

Removing sliver polygons in ArcGIS Desktop?

I unioned 2 layers into 1 layer, and it created sliver polygons. I used the elimination tool to merge them with neighboring polygons. As as result, it merges all sliver polygons to only one polygon ...
6
votes
1answer
585 views

Filling a polygon with lines using Postgis

i need to calculate a specific distance in an area. The distance is calculated from parallel lines in a polygon, And i need to find out how many parallel lines (with x meters distance to each other) ...
1
vote
2answers
439 views

Label inside top left corner of polygons

Does anyone know of a tool or procedure to automatically place a label in the corner of a polygon, rather than at the centroid? I am using Mapinfo and know that I can manually place the label ...
7
votes
4answers
1k views

Output PostGIS geometry data as centroid or polygon depending on zoom level (GeoServer)

This is what I want: when I zoom out, cities of the country should appear as points and at a certain level when I zoom in, I want them to appear as polygons (showing the area of the city and ...
3
votes
3answers
532 views

Selecting polygons with a minimum internal straight line value - ArcGIS 10

I have a map of polygons representing forest stands. I am trying to sort through them to find those polygons that have a minimum internal distance of 200 m in a straight line (my field sampling will ...
2
votes
1answer
1k views

How to make a predetermined Polygon (Circle) From 4 Coordinates, The Radius and Center Longitude and Latitude in Openlayers

I know how to make a predetermined Polygon in Openlayers (see below). Please have a look at http://studio.netnrg.co.za/dev/rnd/blake.loizides/openlayers var feature2 = new ...
12
votes
5answers
4k views

Get Raster Values from a Polygon Overlay in Opensource GIS Solutions

I have two layers. A polygon-shape-layer with many tiles and a raster-layer containing CORINE 2006 land cover with many categories in a colourmap. I want to obtain for each polygon in the shapelayer a ...
0
votes
1answer
386 views

Tiff raster display with polygon layer

Does any body have an idea about why *.tiff images are not displayed when added as raster layer to QGIS after adding a vector layer which has a polygon geometry? SOLVED !! In fact the tiff is ...
3
votes
1answer
3k views

How do I rotate the polygon about an anchor point using python script?

I know there would be no tool in arcpy module as such but mignt have in third party modules. I however tried taking the vertices of the polygon and moving using the below formula. but did not get the ...
3
votes
0answers
272 views

How to get all intersections between two simple polygons in O(n+k)? [closed]

Can someone help with a following problem: report all intersections between two simple polygons in O(n+k) where n - is a total number of polygon edges and k - is number of intersections. As a result - ...
2
votes
1answer
752 views

Openlayers Polygon not visible

I have just recently started playing with mapping but have had limited success. I have been able to create/display markers, but in my current project I am trying to display zipcode areas by creating ...
6
votes
2answers
13k views

How to combine adjacent polygons sharing similar trait into single polygon?

I have a large dataset of habitat classes which I have further simplified down into my own unique classes. However, it resulted in there being habitats adjacent to each other with the same forest ...
4
votes
3answers
1k views

How to Clip a Vector File based on certain Raster Values?

I need to clip a vector file based on certain values of a raster (Slope > 2%). I can´t find a direct way to do it. Trying to vectorize the raster first didn´t work. Is there any tool (ArcGIS or ...
3
votes
2answers
955 views

Generate non-overlapping shapes from a buffer

I have a collection of points, and I need to generate shapes around these points. Let's assume that these points are locations of offices and that the shapes are the 'area of responsibility' around ...
6
votes
4answers
8k views

Getting polygons of all countries and ISO-3166-2 subdivisons

In order to do reverse geocoding lookups to find a country (as ISO-3166-1) and the subdivision (as ISO-3166-2) for given coordinates I am looking for a way to get all polygons of all countries and ...
2
votes
1answer
2k views

How to set polygon opacity on openlayers?

I have some prolems showing polygons in openlayer. I want to divide one city in areas. For the moment I have zona1 and zona2. I took lat and long from google maps so I think they are correct. My ...
2
votes
1answer
162 views

How to digitize from a map with additional detail views?

I have a map with a river that includes islands within it. Some islands have a blown up version (detail views) outside of the river showing land ownership details. I would like to make polygons ...
2
votes
0answers
88 views

Determine which points fall within a 3D polygon and export this subset to a flat file

I am working in ArcMap 10 and will have a 3D representation of a zone of transmission. I would like to determine which GPS points fall within this polygon and then export this subset out to a flat ...
4
votes
2answers
598 views

Is it possible to generate a vector polygon from a polygon on a raster image?

I have a raster map which I have extracted from a government report providing flood extent return frequencies. I want to 'snatch' these flood extent polygons (i.e. convert to vector) and I was ...
1
vote
1answer
614 views

I wanting to reproject the vertices of my polygon. I have been able to achieve this for the bounds but having a bit of trouble with the vertices

I wanting to reproject the vertices of my polygon. I have been able to achieve this for the bounds but having a bit of trouble with the vertices. function onFeatureModified(event) { ...
9
votes
7answers
18k views

Get boundary of raster image as polygon in ArcGIS Desktop?

I have a rectangular raster image in ArcGIS. My question is: how can I produce a polygon which is just the extent of the raster image? That is, I want to have a polygon layer with a single ...
1
vote
1answer
617 views

Unproject Radius with Openlayers with CRS:84 Projection

I have made a Openlayers integrated map that lets you draw a circle, On completion of the circle I have told the map to give me , Bounds, Center Long and Lats, and lastly the radius. My problem is ...
5
votes
1answer
253 views

algorithm for displaying holes in a polygon by translating it into several hole-less polygons?

I'd like to plot polygons with holes on a framework that doesn't support holes. The approach to me seems to be to translate the single polygon into several ones adding up to the whole polygon, leaving ...
0
votes
1answer
231 views

One large polygon or many little ones. What is better regarding performance?

I´m designing a geoprocessing service on ArcGIS Server using several nationwide datasets. Currently I´m preparing some of the datasets and I´m wondering if I should dissolve my polygon layers ...
8
votes
5answers
2k views

How to get an ocean shapefile from a very detailed land area shapefile?

I am looking for a possibility to "invert" a shapefile. What I want to do is to convert a shapefile with the continents and islands into a shapefile that has water polygons. The existing ocean ...
2
votes
1answer
1k views

how to get Coodinates after Resizing a feature Openlayers

I'm trying to display the coordinates of a Feature or vector layer after I use the modify radio button to resize my vector, but it does not work, nor on my drag feature. I'm using ...
1
vote
1answer
1k views

How to stop or deactivate draw polygon control after the first polygon has been drawn in Openlayers

I want to only be able to draw one circle on my map and then disable the control. Below is my code, Any suggestions? <html xmlns="http://www.w3.org/1999/xhtml"> <head> ...
0
votes
0answers
714 views

How to remove small polygons in ArcGIS 10 using extension by Gonza2?

Does anybody have experience and success working with the Remove small polygons from a feature class script tool by Gonza2 in ArcGIS 10? The extension works perfectly in previous version of ArcGIS ...
2
votes
1answer
870 views

Conversion of raster features to polylines: skeletonization?

I would like to identify linear features, such as roads and rivers, on raster maps and convert them to a linear vector features (i.e. polylines). I typically use R as my primary GIS, and have posed ...
2
votes
1answer
2k views

merging 2 polygon adjacent to each other using R

I have several shp files which are the components (or tiles) of a map, I have joint all these tiles together to have a large shp file. Then I realized some of the polygon is now splitted into 2 ...
1
vote
1answer
622 views

Aggregate Data between Polygons

I have data at the ZIP3 level and I need to join it to a state file. I also need the data within the zip3 file to be averaged, but for some reason when I use the join tools, i'm not getting the ...
4
votes
2answers
2k views

Is there an easier way to edit polygons in ArcMap?

I am updating woodlot polygons in ArcMap 10. Instead of editing individual verticies, is there a way to edit that is more like drawing part of a new shape (say if the woodlot has expanded only on one ...
9
votes
1answer
380 views

Efficient raster sampling of billions of polygons (bounding boxes)

How can a raster be computed efficiently (in Python), given a set consisting of billions of bounding boxes (read sequentially from a file), and given that the raster values for each cell should give ...
2
votes
1answer
2k views

How to get the radius of a “circle” in Openlayers

How do you get the radius of a circle in openlayers? I have searched quite a bit and cannot find any resource for this. please help. Here is my code but I want the radius or circumference of the ...
2
votes
2answers
1k views

Openlayers Vector Layer Polygons not displaying properly with OSM

I have an Openlayers map displaying Acetate tiles in OSM, and I'm drawing polygon regions on a vector layer to represent the countries of the world. This works fine for the most part, however, there ...
3
votes
1answer
277 views

Best Method for Validating polygons?

I would like to assess the spatial accuracy of a load of polygon shapefiles which are supposed to show air quality for a bunch of countries. Firstly I want to assess whether each shapefile has a ...
2
votes
1answer
648 views

How do I subdivide and edit polygons preserving topology?

I'm using QGIS. I have a layer made up of many adjacent polygons - let's call them "countries". I currently use the Atlas plugin to export each "country" polygon to a .png file. I want to further ...
21
votes
3answers
4k views

How can I calculate the average width of a polygon?

I'm interested in examining the average width of a polygon that represents the road surface. I also have the road centerline as a vector (which is sometimes not exactly in the center). In this example ...
4
votes
1answer
361 views

Determining if Polygon Contains Negative Space using ArcGIS SOAP Web Service?

I am running queries against a polygon layer using the ArcGIS SOAP Web Service. A user selects a point within that layer and the resulting feature set contains PolygonN objects. Occasionally, the ...
0
votes
1answer
641 views

CenterPoint of Polygon in ArcEngine .Net 10

I am currently trying to get the center point of a polygon. In GIS, i can see the "x" mark in the center of the polygon, but I do not know how to get it from the IPolygon object. I tried getting the ...
0
votes
1answer
1k views

How to change events in the Oncomplete Drag function in Openlayers

below is code that works for Openlayers drag function: drag = new OpenLayers.Control.DragFeature(polygonLayer, { autoActivate: true, onComplete: function() {alert('Are you sure this is the ...
6
votes
2answers
2k views

How to disable polygon Label on the vertices (OpenLayers) in Edit Mode

I added the style on the polygon layer like so. var style = $.extend(true, {}, OpenLayers.Feature.Vector.style['default']); // get a copy of the default style style.label = "1233456 ha" ...